Line an 8 1/2-by-4 1/2-inch loaf pan with waxed or parchment paper, allowing the paper to hang over both long sides.

In a large bowl, beat the cream and sugar until stiff peaks form.

In the bottom of the pan, arrange 3 of the sandwiches in a single layer, cutting them to fit as necessary. If using coffee liqueur, sprinkle the sandwich layer with the liqueur. Spread with half the whipped cream. Repeat with the remaining sandwiches, if using the liqueur,sprinkle ice cream sandwiches with some of it, and top with the whipped cream.

Sprinkle the top of the cake with the chopped chocolate chips. Cover with plastic wrap and freeze until firm, at least 1 hour and up to 1 week.

Holding both sides of the paper overhang, lift the cake out of the pan and transfer to a platter. Discard the paper and serve.